The term “iron-containing metalliferous feed material” is understood herein to include as iron ores, partly reduced iron ores, and iron-containing waste streams (for example, from steelmaking plants).
A known molten bath-based direct smelting process is generally referred to as the HIsmelt process. In the context of producing molten iron, the HIsmelt process includes the steps of:
(a) forming a bath of molten iron and slag in a direct smelting vessel;
(b) injecting into the bath: (i) a metalliferous feed material, typically iron ore in the form of fines; and (ii) a solid carbonaceous material, typically coal, which acts as a reductant of the iron ores and a source of energy; and
(c) smelting metalliferous feed material to iron in the bath.
The term “smelting” is herein understood to mean thermal processing wherein chemical reactions that reduce metal oxides take place to produce molten metal.
In the HIsmelt process metalliferous feed material and solid carbonaceous material are injected into the molten bath through a number of lances/tuyeres which are inclined to the vertical so as to extend downwardly and inwardly through the side wall of the smelting vessel and into a lower region of the vessel so as to deliver at least part of the solids material into the metal layer in the bottom of the vessel. To promote the post-combustion of reaction gases in an upper part of the vessel, a blast of hot oxygen-containing gas, typically air or oxygen-enriched air, which may be oxygen-enriched, is injected into an upper region of the vessel through a downwardly extending lance. Off-gases resulting from the post-combustion of reaction gases in the vessel are taken away from the upper part of the vessel through an off-gas duct. The vessel includes refractory-lined water cooled panels in the side wall and the roof of the vessel, and water is circulated continuously through the panels in a continuous circuit.
Typically, molten iron produced in direct smelting processes such as the HIsmelt process contains concentrations of sulphur that are considerably higher than sulphur concentrations specified for steel. Therefore, desulphurisation of iron produced in direct smelting processes is necessary in order for the iron to be used in the production of steel.